I recently traded someone for a couple of discs... one of them had some paint (not dye) on the top of it where a person had decided to put a design on.. but I figured acetone would easily take care of the issue. Well I took acetone to it and removed the paint, but it looks like in order to create the design they may have done a really crappy job cutting out out the stencil WHILE it was on the disc. There are noticeable lines cut into the flight plate of the disc, though they are all very shallow.

So.. I don't know if this thing is legal to throw or not.

These are the only rules I could find that I thought related... both from 802.1 of the rules...

C. Players may not make post-production modification of discs which alter their original flight characteristics. This rule does not forbid inevitable wear and tear from usage during play or the moderate sanding of discs to smooth molding imperfections or scrape marks. Discs excessively sanded or painted with a material of detectable thickness are illegal. See sections 802.01 D, E and F.

F. All discs used in play, except mini marker discs, must be uniquely marked in ink or pigment-based marking which has no detectable thickness. A player shall receive a warning for the first instance of throwing an unmarked disc if observed by two or more players of the group or an official. After the warning has been given, each subsequent throw by the player with an unmarked disc shall incur one penalty throw if observed by two or more players of the group or an official.

Now I don't think the these cuts alter the flight but some may argue they do. I don't really see them any differently than how a tree would take a chunk out of the disc. The flight plate is not perforated all the way through, so I don't think that's an issue. F is where I have the most concern. There is not added detectable thickness, it's an impression into the plastic instead. I get if the paint was still on there the disc would be illegal according to part F of 802.1.